The present invention relates to a serial printer and, more particularly, to a serial printer of the type in which a disc-shaped carrier carrying a multiplicity of type elements is moved in the line and column directions, and the type element of the desired character is forced out from the plane of the carrier to effect a printing on a recording paper.
An electronic printer having a type wheel having a plurality of spokes having respective type elements on their ends is known for use as a serial printer of the type mentioned above, and is generally referred to as a printwheel. In such known printers incorporating a printwheel, the shifting of the carriage and the rotation of the printwheel are typically controlled by different motors. Also, the carriage necessitatingly carries a hammer assembly and a large-sized electromagnetic hammer actuating means. In consequence, the size of the carriage is increased impractically resulting in an increased size and raised cost of the printer as a whole. Thus, this known serial printer is not suitable for use in combination with small-sized desk-top type calculator and the like.
On the other hand, there is an increasing demand for a desk-top type calculator incorporating such printing means, as a result of the diversification of the functions of the desk-top type calculators. From a commercial point of view, the printing device for use in the desk-top type calculator is preferably an impact type serial printer which has various advantages such as clean printing, simple construction and capability of printing on ordinary paper.
To meet this demand, a serial printer in which the selection of type, driving the hammer and shifting the carriage are performed by a common motor, such as, for example, is described in the U.S. Pat. Appln. Ser. No. 166,774 (filed July 8, 1980) and U.S. Pat. Appln. Ser. No. 178,891 (filed Aug. 8. 1980) has been proposed. These serial printers, although compact and light-weight, have a problem that, because the printing is effected on a paper interposed between a type ring and the hammer, the printing is sufficiently made only on a thin paper such as a rolled paper but cannot be made successfully on the comparatively thick paper such as cards, envelopes or the like. In addition, noise is inevitably produced as a result of the contact between the type ring and the hammer.